CT-free planning for reverse total shoulder arthroplasty - why and how to do it

The most recent Australian Orthopaedic Association's Joint Replacement Registry reveals that the use of CT scans prior to shoulder arthroplasty is increasing rapidly.

This use needs to be considered in light of five factors

(1)  Evidence is lacking that preoperative CT planning improves patient-reported outcomes, complication rates, or revision rates for common arthroplasty cases:

Use of Preoperative CT Scans and Patient-Specific Instrumentation May Not Improve Short-Term Adverse Events After Shoulder Arthroplasty: Results from a Large Integrated Health-Care System found "no reduction in the risk of aseptic revision was observed for patients having preoperative CT scans".

The influence of computed tomography preoperative planning on clinical outcomes after anatomic total shoulder arthroplasty: a matched cohort analysis found the differences in clinical outcomes between the CT and non-CT scan groups failed to meet a clinically significant threshold.

Templating in shoulder arthroplasty - A comparison of 2D CT to 3D CT planning software: A systematic review did not find evidence demonstrating differences in time, cost, functional outcomes, complications, or patient satisfaction.

3D CT-Based Preoperative Planning and Intraoperative Navigation in Reverse Shoulder Arthroplasty: Early Clinical Outcomes did not find statistically significant benefit of CT-based navigation with respect to complication rate, radiographical glenoid notching, and clinical outcomes

Assessing the Value to the Patient of New Technologies in Anatomic Total Shoulder Arthroplasty did not find evidence that the patient outcomes for shoulder arthroplasty were statistically or clinically improved with the use of advanced technologies, such as CT based planning.

(2) CT scanning and 3D planning increase the cost of healthcare by dint of their own costs. But they also initiate a "cost cascade" by driving the use of more expensive implants, and by driving the use of expensive "transfer technologies", such as patient specific instrumentation, virtual and augmented reality, and robotics. Because planning software packages are proprietary, they can drive the use of the implants associated the software, rather than the implants that may be more cost effective.

The influence of three-dimensional planning on decision-making in total shoulder arthroplasty. found 3-D planning influenced the choice of implant 

Impact of preoperative 3-dimensional planning and intraoperative navigation of shoulder arthroplasty on implant selection and operative time: a single surgeon's experience. found an almost three-fold increase in the use of the more expensive augmented components when using 3D preoperative planning 

Computer navigation re-creates planned glenoid placement and reduces correction variability in total shoulder arthroplasty: an in vivo case-control study. found that patients undergoing computer-assisted shoulder arthroplasty had more than twice as many augmented glenoid components as the conventional group 

However, none of these studies presented costs or clinical outcomes comparisons and thus it cannot be ascertained whether the use of augmented components was a cost-effective intervention or not.

Preoperative planning in reverse shoulder arthroplasty: plain radiographs vs. computed tomography scan vs. navigation vs. augmented reality concluded that further research is needed to determine the added value of these technologies in terms of improving clinical outcomes for the patients. The scarce evidence comparing short-term clinical outcomes of RSA with and without the use of these technologies show no or marginal benefits "Any benefit should be balanced against the increased costs and the 200 to 1,000-fold increase in radiation exposure associated with the CT scans in comparison with radiographs ".  

(3) Thus, In addition to its cost, CT scanning is associated with an increased lifetime risk of cancer

Computed Tomography for Preoperative Shoulder Arthroplasty Planning: Lifetime Malignancy Risk: The current reliance on preoperative shoulder CT for arthroplasty planning needs to be weighed against the potential lifetime cancer risks.

Projected Lifetime Cancer Risks From Current Computed Tomography Imaging found that at current utilization and radiation dose levels, CT examinations in 2023 were projected to result in approximately 103 000 future cancers over the course of the lifetime of exposed patients. If current practices persist, CT-associated cancer could eventually account for 5% of all new cancer diagnoses annually.

(4) Reverse shoulder arthroplasty (RSA) is a highly successful operation in the population-based study by the Australian Orthopaedic Association with 10 year revision rates under 6%. Note that these national data include all cases performed by all surgeons, not only "high volume" surgeons.

Complications and revision of reverse total shoulder arthroplasty found that 40% of revisions were for infection, 20% for instability/dislocation, 20% for loosening, and 10% for fracture. Evidence is lacking that CT scans, CT-based planning, and associated technologies have a substantial impact on these common reasons for RSA revision. 

Patient-Specific Instrumentation Versus a Free-Hand Technique for Glenoid Baseplate and Peripheral Screw Placement in Reverse Total Shoulder Arthroplasty Using the Exactech Implant System: A Multicenter Randomized Controlled Trial concluded "in primary rTSA, PSI did not improve glenoid baseplate positioning compared to a free-hand technique"

(5) In most cases, cost-effective preoperative planning can be efficiently carried out without a CT scan. 

Here's a way to it in under ten minutes using the Picture Archiving and Communication Systems (PACS) tools applied to two standardized preoperative plain films (AP view in the plane of the scapula and axillary view). This approach is generic and is not tied to any commercial company, allowing surgeons to have their choice of implant. It can be used by essentially all shoulder surgeons. It provides an approach for transferring the plan to the patient. It is cost-effective - an important feature, especially at this time when many are having difficulty affording health care.

Step 1, on the AP view, draw a line along the base of the supraspinatus fossa (yellow line in right hand image).

Step 2, draw a line segment  equal to the radius of the base of the glenosphere from the inferior glenoid at a right angle to the supraspinatus fossa line so that it intersects the glenoid face (yellow line on left image below). This intersection will be the starting point for the drill for the central scew of the baseplate. This point will be located at surgery by measuring the distance from this point to the inferior lip of the glenoid (yellow line on right image below). Note that the amount of bone that will be removed by reaming is represented by the triangle in between these two lines.

Step 3 Draw a line parallel to the supraspinatus fossa line that intersects the glenoid face at the insertion point (yellow line on left image); this is the trajectory of the drill. Measure the angle between this line and the face of the upper glenoid (yellow line on right image) to guide the tilt of the drill at surgery.

Step 4 On the axillary view, draw the desired trajectory of the central screw so that it will just penetrate the anterior cortex of the subscapularis fossa when fully inserted (central image). Note the angle of this line with the gleniod face (right image) to guide version of drill at surgery.

The resuling arthroplasty closely approximates the plan.

Another example

And another

CT-free planning is consisted with the philosophy expressed in the preface of Practical Evaluation and Management of the Shoulder (1994): "This book is directed at the type of practice we see evolving for the coming decades, when resources will not be as plentiful and increasing premiums will be placed on economy and effectiveness. In this spirit, we emphasize what can be accomplished with the basics: the clinical history, the physical examination, a few plain radiographs, simple patient-conducted rehabilitation programs, and well-characterized surgical procedures. "

Thanks to our two shoulder fellows, Jake Checketts and Dave Daniels, for their help with this post. They easily mastered this method and routinely apply it to all but the unusual cases of reverse shoulder arthroplasty (i.e. those with severe bone loss, complex revision cases, significant deformity).

Making a Plan

Osprey 

Union Bay Natural Area

2024

Follow on twitter/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link)
The total shoulder arthroplasty (see this link)
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link)
Shoulder rehabilitation exercises (see this link).

Glenoid version: acceptors and correctors

At a recent Cantina luncheon, conversation among five shoulder surgeons concluded that shoulder surgeons are becoming divided with respect to their approaches to arthritic shoulders with glenoid retroversion: there are the "acceptors" and  the "correctors".

The acceptors ream the glenoid only enough to create a smooth concavity that corresponds to the backside of the glenoid component. The correctors strive to reduce glenoid retroversion to 15 degrees or less, using posteriorly augmented glenoid components, anterior "high side" reaming, or posterior bone graft. 

The acceptor approach requires only standardized plain radiographs and the occasional use of anteriorly eccentric humeral head components and rotator interval plication if excessive posterior decentering is noted at surgery. 

By contrast, the corrector approach usually requires a preoperative CT scan, three dimensional planning, and some means of carrying out the plan in the operating room, such as patient specific instrumentation or computer guidance.

The literature available to date does not demonstrate a superiority of either approach in terms of clinical outcomes in the management of arthritic shoulders with a retroverted glenoid.

It is of interest to see how the corrector and acceptor approaches are used in a membership-based, dues prepaid, direct health care system, where optimization of both outcome as well as total outpatient and inpatient costs are priorities. The authors of Use of Preoperative CT Scans and Patient-Specific Instrumentation May Not Improve Short-Term Adverse Events After Shoulder Arthroplasty showed how the corrector-oriented technologies - preoperative computed tomography (CT) scans and patient-specific instrumentation (PSI) - are used in their integrated health-care system.

They identified 8,117 primary elective anatomic or reverse total shoulder arthroplasties (7,372 patients) performed by 130 surgeons between 2015 to 2020 with an average follow-up of 2.9 years (maximum, 6 years).  

During the period of this observational study, the 130 surgeons in this healthcare system chose to use preoperative CT scans in less than half of the primary shoulder arthroplasties and to use PSI in one out of nine cases. 

CT Scans

The use of preoperative CT scans is probably associated with the surgeons' desire to correct preoperative glenoid version.

Over the period of this study it appears that the surgeons became more selective in their use of preoperative CT scans:

(1) less than half of all shoulder arthroplasty patients had preoperative CT scans; this percentage trended downward with time

(2) patients with glenoid types B1 and B2 were slightly more likely to get preoperative CT scans, whereas patients with A1 glenoids were slightly less likely to have CT scans; yet for each glenoid type, less than one third of patients had preoperative CT scans

The arthroplasty surgery of patients having CT scans took 12% longer and had somewhat higher cumulative revision rates

and had a higher likelihood of venous thromboembolism (OR = 1.79; 95% CI = 1.18 to 2.74) compared with those without CT scans.

Patient Specific Instrumentation

The use of PSI is probably associated with the surgeons' desire to correct preoperative glenoid version.

3553 (44%) of the patients received a Tornier implant; of these 400 (11.3%) had their implants inserted using patient specific instrumentation. Shoulders with PSI were more likely to be male and to have a Walch type B or C preoperative glenoid pathoanatomy. Surgical procedures using PSI also had a longer mean operative time. 

The patients receiving arthroplasty with PSI had slightly increased rates of early revision.

Patients with PSI use had a higher likelihood of 90-day deep infection (OR = 7.74; 95% CI = 1.11 to 53.94), which may be related to the increased OR time.

 

Comment: At this point it is not clear how much "correction" of version is necessary to obtain a great outcome for the patient.

In Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty? the authors presented a series of anatomic total shoulders in which neither 3D imaging or PSI was used; postoperative glenoid retroversion was not associated with inferior clinical results at 2 years after surgery.

Glenoid retroversion does not impact clinical outcomes or implant survivorship after total shoulder arthroplasty with minimal, noncorrective reaming found reliable increases in patient satisfaction and clinical outcomes in patients with up to 40 degrees of retroversion.

Baseplate retroversion does not affect postoperative outcomes after reverse shoulder arthroplasty. found no significant difference in postoperative functional outcomes, range of motion, or complications between patients who had baseplate retroversion ≤15° vs. those who had retroversion >15°.

Many of the published articles discussing CT planning, PSI and computer guidance focus on the accuracy and precision achieved with the techniques rather than clinical outcomes; see 

Accuracy of 3-Dimensional Planning, Implant Templating, and Patient-Specific Instrumentation in Anatomic Total Shoulder Arthroplasty. 

Version and inclination obtained with 3-dimensional planning intotal shoulder arthroplasty: do different programs produce the same results?

The influence of three-dimensional planning on decision-making in total shoulder arthroplasty.

Patient-specific Guides Using 3-dimensional Reconstruction Provide Accuracy and Reproducibility in Reverse Total Shoulder Arthroplasty.

Patient-specific instrumentation for total shoulder arthroplasty: not as accurate as it would seem.

Accuracy of patient-specific instrumentation in shoulder arthroplasty: a systematic review and meta-analysis.

Commercial 3-dimensional imaging programs are not created equal: version and inclination measurement positions vary among preoperative planning software.

Strategies to assist in the correction of glenoid pathoanatomy have not been associated with clinically significantly improved patient outcomes.

For example, the authors of The influence of computed tomography preoperative planning on clinical outcomes after anatomic total shoulder arthroplasty: a matched cohort analysis. did not find a clinically significant difference between the outcomes of total shoulders performed without and with 3D CT planning. 

In Patient-specific Instrumentation Versus Standard Surgical Instruments in Primary Reverse Total Shoulder Arthroplasty: A Retrospective Comparative Clinical Study, patient having RTSA with PSI did not achieve significantly different clinical outcomes than those without PSI. 

The authors of Early clinical outcomes following navigation-assisted baseplate fixation in reverse total shoulder arthroplasty: a matched cohort study found that navigated and non-navigated RSAs yielded similar rates of improvement in range of motion and functional outcome scores.

Assessing the Value to the Patient of New Technologies in Anatomic Total Shoulder Arthroplasty. found that since the advent of preoperative computed tomography (CT) scans, 3-dimensional preoperative planning, and patient-specific instrumentation there is a lack published evidence that the results of TSA have been statistically or clinically improved.

In conclusion, more research is needed to determine the clinical outcomes for the corrector and acceptor approaches to shoulders with different degrees of glenoid retroversion.

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link.

Follow on twitter: https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).

Is Preoperative Three-Dimensional Planning and Intraoperative Navigation of Shoulder Arthroplasty of Value?

The Impact of Preoperative Three-Dimensional Planning and Intraoperative Navigation of Shoulder Arthroplasty on Implant Selection and Operative Time: A Single Surgeon’s Experience

These authors assessed the impact of preoperative 3D planning on the surgeon’s selection of the glenoid component (standard versus augmented) and compare duration of surgery with and without intraoperative navigation in 200 patients who underwent shoulder arthroplasty. 

The first group of 100 patients underwent shoulder arthroplasty utilizing standard 2D preoperative planning based on standard radiographs and CT scans. 

The second group of 100 patients underwent shoulder arthroplasty utilizing 3D preoperative planning and intraoperative navigation. 

For the group of patients with standard preoperative planning, only 15 augmented glenoid components were utilized while in the group of patients with 3D preoperative planning and navigation 54 augments were used. 

The operative time was 11 minutes longer for the procedures that used intraoperative navigation, compared to those that did not.

Comment: While this study showed that the surgeon's choice of implant was affected by the use of preoperative three-dimensional planning and intraoperative navigation of shoulder arthroplasty, it does not show that this effect benefitted the patient in that clinical outcome and survivorship data were not presented. As the authors state, "Since 3D planning and  intraoperative navigation is more costly than 2D planning, and augmented glenoid components are more costly than standard glenoid components, the cost-benefit of these changes with  respect mid-term and long-term clinical outcomes and implant survival has not been ascertained."

Data from the Australian Orthopaedic Association registry, shows that the 10 year revision rate for cross-linked all-polyethylene components inserted without preoperative three-dimensional planning, intraoperative navigation, or augmented glenoid components is below 5% (see below). One must ask "How likely is it that these more expensive technologies will lead to better outcomes than these?"

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To see a YouTube on how we do total shoulder arthroplasty with an emphasis on glenoid preparation, click on this link.

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How you can support research in shoulder surgery Click on this link.

To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Should we be spending money on computer-assisted technologies in arthroplasty?

Computer-Assisted Technologies in Arthroplasty. Navigating Your Way Today

In this article about hip and knee arthroplasties, the authors point out that computer-assisted technologies that are used in arthroplasty include navigation, image-derived instrumentation (IDI), and robotics.

However they also point out that it is not clear whether the implementation of these technologies improves the clinical outcome of surgery and that high cost and time demands have prevented the global implementation of computer-assisted technologies.

They did not model the effect of CT scanning on the risk of cancer for the patient.

Especially in these times with huge strains on the nation's medical budget, we need to be thoughtful about how our health care dollars are spent.

It is of interest to see how different countries have moved to adopt CT technologies in hip and knee arthroplasty

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How you can support research in shoulder surgery Click on this link.

We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Does a preoperative CT scan improve patient outcomes?

Comparing the Use of Axillary Radiographs and Axial Computed Tomography Scans to Predict Concentric Glenoid Wear

These authors sought to compare the use of axillary radiographs and midglenoid axial CT scans to identify glenoid wear.

Five independent examiners with differing levels of experience characterized the glenoid morphology as either concentric or eccentric on preoperative axillary radiographs and mid-glenoid axial CT scans for 330 patients who underwent anatomic total shoulder arthroplasty.

Intraobserver consistency averaged 75% for radiographs and 73% for CT scans. There was significant interobserver consistency, as higher levels of training corresponded with greater consistency between imaging analyses (p < 0.001).


Comment: Especially in these times with huge strains on the nation's medical budget, we need to be thoughtful about how our health care dollars are spent.

As the authors state, "Although CT scans are associated with greater financial cost and exposure to radiation than radiographs, the literature has yet to describe the additional clinical value and/or potential cost-value benefit as a result of improved outcomes provided by the use of CT scans in patients undergoing total shoulder arthroplasty, even when integrated with virtual planning software and generation of patient specific instrumentation."

We agree that CT scans without or with 3D reconstructions can provide additional detail regarding glenohumeral pathoanatomy in comparison to plain radiographs, it remains to be seen whether this increment in information leads to significantly better clinical outcomes for the patient. Any benefit would need to be balanced against the increased costs and the 200 to 1,000 fold increase in radiation exposure of the CT scans (2.06 mSV)75 (10.83 mSV)76 in comparison to plain radiographs (0.01 mSV). In addition to the cost, physicians are increasingly concerned about the relationship between radiation dosage and the risk of the patient developing cancer.

Further research is needed to show that preoperative CT scans contribute to improved outcomes for the patient.

Meanwhile, standardized preoperative views can provide the information needed to evaluate and manage the arthritic shoulder (see article below).

Prearthroplasty glenohumeral pathoanatomy and its relationship to patient’s sex, age, diagnosis, and self-assessed shoulder comfort and function

These authors examined 544 patients within 6 weeks before shoulder joint replacement arthroplasty with the goals of characterizing the radiographic characteristics of the arthritic joint and the relationship of these pathologic changes to the patients' age, sex and diagnosis. They also studied the inter-relationships among glenoid type, glenoid version, and amount of decentering of the humeral head on the glenoid; as well as the relationships of the pathoanatomy to the patient’s self-assessed shoulder comfort and function.

Examples of the different types of glenoid pathoanatomy are shown below.

They found that male patients had a higher frequency of type B2 glenoids and a lower frequency of A2 glenoids.

The arthritic shoulders of men were more retroverted and had greater amounts of posterior decentering.

Patients with types A1 and C glenoids were younger than those with other glenoid types. 

Shoulders with osteoarthritis were more likely to be type B2 and to be retroverted. 

Types B2 and C had the greatest degree of retroversion, whereas types B1 and B2 had the greatest amounts of posterior decentering. 

Shoulders with glenoid types B1 and B2 and those with more decentering did not have worse preoperative self-assessed shoulder comfort and function.

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To see a YouTube of our technique for total shoulder arthroplasty, click on this link.

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How you can support research in shoulder surgery Click on this link.

To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Not Becoming a Robot with the Industrialization of Medicine

Not Becoming a Robot with the Industrialization of Medicine

This venerable author points out the risk of using technology rather than basic clinical skills when evaluating and managing patients.

A couple of sentences were eye catching. 

"Examinations such as MRI and CT may cost 4 to 5 times more than ordinary radiographs. In many cases, however, much less expensive radiographs—preceded by a detailed careful history and physical examination—may suffice for making the diagnosis and treatment".

"We also must remember that not all diagnostic tests are harmless. Take, for instance, a CT scan. The amount of radiation exposure to one’s body from a CT scan is 50 to 100 times more millisieverts than that of an ordinary chest radiograph. The effects of this radiation stay in the body permanently and are additive. Cumulative radiation to surgeons from radiographs over 15 to 20 years increases the risk of cancer by 3 to 5 times "

These thoughts surely apply to the evaluation of the arthritic shoulder. See our approach to the cost effective imaging of shoulder arthritis in this link.

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To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.

Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages  arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Glenoid version before and after arthroplasty.

Determining glenoid component version after total shoulder arthroplasty

These authors examined the issue of measuring postoperative glenoid version, pointing out that postoperative CT scans add cost and radiation exposure (of course preoperative CT scans also add cost and radiation exposure as well).

They present a method for assessing glenoid component version after TSA using preoperative CT and postoperative plain radiographs.

Preoperative glenoid version was measured using established methods with an axillary x-ray, 2-dimensional CT, and Glenosys software. 

Postoperative glenoid component version and inclination were measured using Mimics software with preoperative CT and postoperative x-rays. 

It is interesting to see how closely the values for retroversion obtained with axillary x-rays correlated with those obtained using various CT-based methods

Similarly the preoperative to postoperative change in glenoid version was similar with the different methods of preoperative measurement.

The authors point out that the Mimics protocol requires purchase of specialized software, becoming proficient in software 3D modeling, and approximately 30 minutes spent on each patient’s evaluation and analysis due to a lack of specific programming to automate the protocol.

Comment: In an effort to carry out side-by-side comparison of preoperative and and postoperative glenoid version in a practical manner without the added cost and radiation of CT scans, it seems to make the most sense to use standardized axillary views taken in a functional position of elevation in the plane of the scapula

Here are two preop-post op comparisons. Note the standardization of portion and projection.

As for "correcting" preoperative glenoid version, it may not be as important as once thought, click on this reference:

Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty?

To see a YouTube of our technique for total shoulder arthroplasty, click on this link.

=====

We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link

Use the "Search" box to the right to find other topics of interest to you.

How you can support progress in shoulder surgery

You may be interested in some of our most visited web pages arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'